Fastening devices, such as staplers, staple, brad, nail and connector guns are commonly used in the home, in offices, industry and construction. A feature common to most fastening devices using fasteners which are supplied in a frangible stick, e.g., staples or brads, is the use of a spring-biased magazine follower to push the stick of fasteners forward in the magazine towards the operating end of the fastening device. This has the effect of feeding the fasteners sequentially and continuously into the operating end of the fastening device, and maintaining the first fastener, i.e., the next fastener to be dispensed, in proper position for dispensing. Magazine, as used in this application, denotes a receptacle for receiving therein a quantity of fasteners, and which stores and sequentially dispenses these fasteners as the fastening device is actuated. Magazines in current use in fastening devices are either integral with the fastening devices or removable therefrom. The spring-biased magazine follower common to these fastening devices may be integral with the magazine, integral with the fastening device or removable from either or both. A common feature of many of these fastening devices is the mounting of the magazine follower on a follower rod, upon which the magazine follower is slidably mounted. Many of these fastening devices utilize a removable magazine follower assembly which comprises the magazine follower, follower rod, bias spring and closure device. The closure device typically has mounted on it the follower rod, and serves to close the magazine and hold the fasteners therein. The bias spring is also mounted on the follower rod, between the magazine follower and the closure device. A failing of many of these fastening devices is that there is no convenient means for measuring the amount of fasteners remaining in the magazine without some disassembly of the device. Often, the only means available to determine the quantity of fasteners remaining in the device is to manually remove the fasteners from the device, or at least to open the device for visual inspection. In an office environment, running out of staples in the midst of a project is a minor annoyance. On a construction site however, when a construction worker may for reasons of distance or ease of access lack ready availability to his source of fasteners, knowing how many fasteners remain in the fastening device may enable a worker to realize significant savings in labor expended. Having to stop work in order to open the fastening device and visually inspect the fastener quantity is inefficient, and given the conditions on some construction sites, may be potentially dangerous.
A system utilized in some fastening systems is the use of open-sided magazines for displaying directly the amount of fasteners remaining in the device. While this methodology is often seen in nail guns, it is seldom found in staplers, staple guns, brad guns and the like used for installing a wide variety of patent fasteners and connectors. The magazine follower is an accurate indicator of the quantity of fasteners remaining in the fastening device. If some means could be found for showing the position of the magazine follower in the magazine without disassembly of the fastening device, the quantity of fasteners contained therein could be established by immediate external visual inspection.
What is needed is a method or apparatus for measuring the quantity of fasteners contained in the magazine of a fastening device without disassembling the fastening device and indicating, at a glance, that quantity to the user. This method or apparatus could use the position of the magazine follower to drive an indicator means for indicating the quantity of fasteners in the fastening device. In fastening devices with removable magazine follower assemblies, the apparatus should be capable of being effected without re-designing or re-tooling the existing fastening device. Where the fastening device lacks a removable magazine follower assembly, the principles of the present invention should be employable without extensive modification of the existing design.